Calutron



A ril 14, 1959 E. o. LAWRENCE ET AL 2,832,407

CALUTRON Filed May 14, 1946 2 Sheets-Sheet i 1NVENTOR v fRA/EST 0 LAW/FENCE W/AL MM Mfi/POBECK m gdulfl M P ATTORNEY Apnl 14, 1959 E. o. LAWRENCE ET AL 2,832,407

CALUTRON I Filed May 14, 1946 2 Shets-Sheef 2 S5 0 )6 1M 1 MW y. M a W 5 0 w #w VW 2. 0F 0 0 i m I qlll'lllllll'll ,QOIIIII I i ATTORNEY United States PatentQ M TheLinventiontIeIates means: especially effectivezto .515 products. ions :and :particularly. to an ionproducingmeansicz of-the1naturereferredcto as a -.calutron.i. Such a device? is disclosed imoreiparticularly in-.thehU s Patent i. No: r 2,709,222 issued..May.-..24, .1955, to Ernesto; Lawrencers Several forms of calutron are disclosed in the Lawrence;: 2 patentiand thei one itO which .the present inventioni most closelylappertains is especially disclosed in Figures"?! to 5, ofethatscase.

Some'ionizing mechanisms;iiparticnlarly those oil the calutroniitype', generally utilize as a means for produc ing'uions -.an :electrici arcsstruckxbetween :a cathode andn anzanode; with the length :of the: arc 'substantially 'iparallel to a. magnetic field within which the structureioperates;::;.The material to' be ionized, usually in vap'oror gasfform; iis caused to flow toth'e vicinity of -orthrou'ghc-ithetarc and collisions between the arc electronsandthemoleculesof the vapor induce the formation of a number of:i'ons that are. subsequently withdrawn from the arc or its vicinity :by means of a suitable-structure such as an accelerating electrode. It is quite important in the-"pro duction' of-ions-by this-means that the gas-0r vapor be caused-toflowin as'uniforma fashion as. possible in en-- countering the are.

It is therefore an object of our invention to provide 1 means for improving the arc structure and its surroundings in a device in the nature-ofa calutron;

More specifically, it is anobject of the present inventionto provide for controlled vaporization of a materia1- to be ionized and controlled flow of the vapor to an ionizing zone.

It :is a featureof the. present'inve'ntion to providean ion source comprising three communicatingxzones "or chambers, in the first of which charge material is vaporized, and flows through the second or distributing chamber to the third or are chamber.

It is a further feature of the present invention to provide an ion source having a distributing chamber connected between a vaporizing chamber and an arc chamber, and means for maintaining said distributing chamber at an elevated temperature with respect to said vaporizing chamber.

Other objects not specifically described above will become apparent as the description proceeds, especially when taken in conjunction with the accompanying drawings, in which:

Figure l is a fragmentary view of a portion, particularly the source unit, of a calutron, a portion of the figure being disclosed in cross-section on a vertical, median plane and portions of the figure being broken away to reduce its size;

Fig. 2 is an isometric perspective of the source mechanisms and its immediately adjacent structure as illustrated in Fig. 1 but with portions being broken away to disclose the interior arrangement; and

Fig. 3 is a side elevation of the structure shown in Fig. 2.

2,882,407 Patented Apr. 14, 1959 2 While :a calutron is described in considerable detai in :ithe" above-identified patent of --=Lawrence, a briefre s view ofthat structure will suffice -for an understandingof 5 thepresent development-"and is given in connection with Fig- 1.-

In a calutron there is-provided a volume 6 permeatedby a uniform or homogeneousmagnetic field e'stablished between the upper pole 7 and the loWer-pole 8 of an-- electromagnet. Disposed between thepoles-7 and 8 and situated :within the magneticfield is a tank or vessel -9 enclosinga volume 11 connected--to suitable pumping mechanism-such as a difiusion pumptno't shown-) eifec tive-normally to evacuate the volume 'll to a pressure of-approximately 1-0 mm. of HgL-Thetank 9 includes a top wall12,-'a bottom wall 13, :anda face plate-14:

Secured removably'to the faceplate'is an insulator 116 1 serving also as a support for a mounting and adjusting mechanism-17 not described in detail herein as its ale-" tailed' f-unctioning-is notxof consequence in connection with the=present"invention.- :The structure 17, however-,-==-- acts as a supportfor a mounting stem-18 of -a source blocle 19. A number of conductors 21 and leads-'22 incIuded-in-the structure 1'7 'passwith'vacuum tightness fro'mutheatmosphereinto-the=interior of the vessel 9. The stem'18 is preferably related to the-source'block 19 by a terminal flange 26 -and-suitable fastenings' 27 so; that while some thermal -insulation-is afiorded -there is nevertheless good electrical contact;

The source-block 19 (Fig. '3) is at its inner endprovided with -a heatercavity 28 closed=by a disk 29 at upper end and'receiving through itslower-end anelectric coil heater 31 mounted on an insulating core 32,- The heater coil is connected to-a pair of leads-33 and'-' 34 one being joined to one end of the conductor 22'and' the other being connected to theblock or fiafige-ze; Upon the -imposition of a suitable potentialditference' by a heater supply 25 between-the conductors '18 and 22,-the' "r heater 31'i-s effectiveto increase the temperature of the-- block 19. The sourceblock preferably is-of metalsothatheat'from the coil 31 is generally conducted in aunifor'm fashion to a distributing cavity 36 form'ed with in the I block 19; 1 The distributing' cavity extends nearly throughthe under side of the block and entirely-through the top-face 37' thereofi- Establishing communication between --the -cavity- -36 an-d the exterior-face 38 of the blocki'l9' is a'gas passage 39 or-- -'arc chamber defined by a' pairxtofiparallel planar walls =41'-'-and- 42 sothaLthe passage is a' straight one:ex#- tending from within the block to the outside thereof and thus merging not only with the face 38 but also with the adjacent face 37.

To close the cavity 36 and a part of the passage 39 there is provided on the face 37 in abutment therewith, a plate 43 fastened to the block 19 by suitable screws 44 and effective to seal one end of the cavity and one end of the passage. The plate 43 preferably extends beyond the face 38 and overhangs the edge of the block 19. The plate is provided, in registry with the passage 39, with an aperture 46 preferably symmetrically disposed with respect to the passage.

Adjacent the block 19 and overlying the plate 43 is a filament 47 held by grips 48 and 49 at the ends of filament leads 51 and 52 connected to a pair of the conductors 21 so that when a circuit is completed, as by a filament supply 50, the filament 47 is heated to electron emission temperature.

When a correct potential difference is supplied by an arc supply 56 between the filament 47 and the block 19, an arc is struck between the filament and the block. The arc passes through the aperture 46 extends down between the walls 41 and 42 and strikes on the bottom 54 of the passageway 39 which, therefore, serves as an anode.

In accordance with the present invention, a separate charge receptacle or vapor generator 60 is provided which, as best seen in Fig. 2, comprises a generally rectangular block, which may be formed of copper. Receptacle 60 is provided with a central chamber 61 for receiving charge material 62. A plate 66 overlies and is adapted to close the open upper end of chamber 61.

Charge material 62 is selected such that it may be vaporized by heat, and a passage 63 is provided for vapor to flow from charge chamber 61 to distributing or heating chamber 36. Specifically, a short tubular section or thimble 64 is provided which connects block 60 to block 19 so as to provide for flow of vapor from chamber 61 to chamber 36, and to assist in mechanically supporting block 60 on block 19. Mechanical support of block 60 is further efiected by a pin 65 shown as recessed into the adjacent walls of blocks 19 and 60.

It will be readily apparent that conduction of heat from block 19 to block 60 will be materially restricted by the small cross-section of the paths provided by thimble 64 and pin 65. Total heat transfer will be increased by radiation from block 19 to block 60. Elementary considerations will show, however, that in all cases the temperature of block 60 will be somewhat less than that of i block 19. This is important since it insures that vapor formed in charge chamber 61 as a result of any temperature therein, will not condense on the walls of distributing chamber 36 or arc or ionizing chamber 39.

Another advantage of the present construction resides in the fact that charge chamber 61 may be substantially filled with charge material 62, without interfering with free and substantially uniform flow of charge vapor from distributing chamber 36 into arc chamber 39 along the entire length of arc chamber 39.

What is claimed is:

1. An apparatus for developing gaseous ions comprising an arc block having an open ended bore extending substantially therethrough, an elongated slot through a wall of said block communicating with said bore and extending from the open ended portion for substantially the length of said bore, a cover plate for said open ended bore having an aperture overlying said slot, heater means included within said block to prevent condensation therein, an electron emissive element disposed in alignment with said aperture and slot, power supply means connected between said element and block for establishing an are along the length of said slot, and a separate vapor generator supported on a wall of said are block by means of a mounting pin and a hollow thimextending from the open ended portion for substantially ble, said thirnble communicating with said bore through an aperture in said block whereby vapor generated in said generator flows into said bore and thence uniformly through said slot.

2. An apparatus for developing gaseous ions comprising an arc block having an open ended bore extending substantially therethrough, an elongated slot through a wall of said block communicating with said bore and extending from the open ended portion for substantially the length of said bore, a cover plate for said open ended side of said block and having an aperture overlying said slot, a heating coil disposed in a chambered portion of said block adjacent said bore, electrical means connected to said coil for heating said bore to prevent condensation therein, a cathode disposed in alignment with said aperture and slot, a power supply connected between said cathode and block for establishing an are along the length of saidslot, and a separate vapor generator supported on .a wall of said block by at least a hollow thimble, said thimble communicating with said bore through an aperturein said block whereby vapor generated in said generator flows into said bore and thence uniformly through said slot.

the length of said bore, a cover plate for said open ended side of said block and having an apertureoverlying said slot, a heating coil disposed'in a chambered portion of said block adjacent said bore, electrical means connected to said coil for heating said bore to .prevent condensation therein, a cathode disposed in alignment with said aperture and slot, a power supply connected between said cathode and block for establishing an are along the length ofsaid slot, a container for material to be vaporized mounted on and spaced from a wall of said block by at least a hollow thimble, said thimble communicating with said bore through an aperture in said block whereby Lamar et a1.: Physical Review, Sept. 1, 1935,'vol. 48, pp. 886-892,

Bleakney Nov. 12, 1940 

